1. Field of the Invention
This invention involves an apparatus for vapor containment and recirculation for use in fluid systems, including pumps and valves. More specifically, this invention provides a closed loop recirculation system for ensuring that vapor does not escape from fluid systems.
2. Description of the Prior Art
Fluid systems and their components, such as pumps and valves, comprise mechanically moving parts. In order for such parts to move with respect to each other, there must be some degree of clearance between them. This clearance provides a flowpath for fluid to escape.
Prior art devices have employed mechanical seals, such as O-rings, to prevent fluid from leaking out of such fluid systems. Mechanical seals are subject to deterioration as a result of mechanical forces and corrosive substances that come into contact with the seals. The exposure of mechanical seals to certain corrosive elements may also weaken the seals' resistance to mechanical forces. For example, polymer-based O-rings may become brittle upon exposure to certain chemicals, thereby increasing the probability that such O-rings will crack or snap in response to mechanical stresses.
Prior art devices have employed both single and double mechanical seals to contain the fluid within a fluid system. Single mechanical seals have comprised a gland, a stationary face or seat, and a rotating face. In one embodiment of the single mechanical seal, all of these elements are contained in a one piece cartridge comprising a sleeve. Such seals leak process fluid across the stationary face and the rotating face in order to lubricate and cool the seal. Such leakage is environmentally unacceptable.
Other prior art devices employ double mechanical seals. Double mechanical seals comprise a barrier fluid at a pressure greater than the fluid pressure of the fluid system. The barrier fluid is circulated within a closed vent system. Double mechanical seals in existence today often involve both high maintenance costs and short life spans.
Fluid systems in common use often contain hazardous, toxic, and/or volatile organic compounds (VOCs). Federal and state environmental laws and regulations are becoming increasingly strict with regard to the release of such substances into the environment. For instance, the Clean Air Act of 1990, enacted by the United States Congress, sets increasingly stricter limits upon the release of selected VOCs through the remainder of this century.
The present invention is directed toward overcoming these problems of prior art vapor containment devices. Specifically, the present invention is directed toward providing a vapor containment system that does not leak VOCs and that has low maintenance costs and a long life span.